Electronic signal-delay device



Aug. 29, 1961 K. F. ROSS ELECTRONIC SIGNAL-DELAY DEVICE Filed Jan. 6, 1959 IN VEN TOR: M?

Filed Jan. 6, 1959, Ser. No. 785,221 Claims. Cl. 315-27 My present invention relates to a device for producing a delayed output in response to a control signal.

For high-frequency signaling, in which even short absolute delay times correspond to substantial fractions of an oscillatory cycle, it is often convenient to use cathode-ray tubes as delay devices. This presents no particular problem if the signal to be delayed is applied to an intensitycontrol electrode of the tube so as to modulate the intensity of the electron beam thereof, this beam then impinging upon a suitable target electrode to deliver an output current proportional to said intensity. In many instances, however, better amplification or other desirable efiects may be obtained by using the signal not to modulate the intensity of the beam but to control its deflection; in these cases the tubes become bulky and unwieldy if a large beam sweep is to be combined with a considerable phase delay.

The general object of my present invention is to provide an improved delay device of the character referred to in which the radial dimensions of a cathode-ray tube are maintained small over the major portion of its length, irrespectively of the magnitude of the delay introduced.

The invention realizes this object by the provision of means at the input end of a cathode-ray tube for deflecting a beam substantially parallel to itself, e.g. by two pairs of cross-connected electrodes or by magnetic means,

atent O i in combination with magnetic focusing means maintaining the beam axially oriented throughout the major portion of the elongated tube envelope. Advantageously, in order to afford increased deflection without material enlargement of the tube, additional deflecting means may be provided at the output end thereof (i.e. near the target electrode) to convert the various parallel beam paths into divergent ones.

The invention will be more fully described with reference to the accompanying drawing in which:

FIG. 1 shows, somewhat diagrammatically, a cathoderay tube embodying the invention adapted to serve as a signal-delay device;

FIG. 2 is a section taken on the line 2-2 of FIG. 1;

FIG. 3 is a view similar to FIG. 1, showing a modified delay device embodying the invention;

FIG. 4 is a section taken on the line 44 of FIG. 3; and

FIG. 5 is a view similar to the right-hand portion of FIG. 1, illustrating a further modification.

In FIGS. 1 and 2 I have shown a cathode-ray tube 10 whose evacuated cylindrical envelope contains an electron gun including an accelerating anode 11 biased positively, relatively to a cathode 12, by means of a battery 13. This gun emits an electron beam 14' toward a target electrode consisting of a body 15 of resistance material bounded by a pair of conductive terminal strips 16', 16", the latter being tied to respective output terminals 17', 17" connected across an output resistor 18 with grounded center tap. Since the anode 11 is likewise grounded, the region between it and target electrode 15 represents a drift space in which the electrons of beam 14 undergo substantially no further acceleration.

A pair of deflecting electrodes 19, 19", connected between ground and a signal-input terminal 20, serve to deflect the beam 14 from the tube axis into a variety of positions of which some, including the extreme beam position 14 and 14", have been indicated in dot-dash lines in FIG. 1. The beam then passes between a pair of horseshoe magnets 21', 21", which may be of the Patented Aug. 29, 1961 permanent type, positioned on either side of the tube axis with relatively inverted polarity so as to produce a field which has a maximum intensity of one sign in the region of beam position 14', goes through zero at the tube axis and has a maximum intensity of the opposite sign in the region of beam position 14".

With proper selection of the dimensions, intensity and relative spacing of magnets 21, 21" it is possible to obtain a field whose strength in the median plane of tube It) varies nearly linearly with the distance from the tube axis whereby, with suitable choice of polarity as indicated on the drawing, the electron beam deflected by electrodes 19, 19" will again be deflected into a substantially axial position irrespectively of the original angle of deflection. The thus re-oriented beam enters the axially extending magnetic field of a conventional focusing coil 22 serving to prevent the electrons from straying from their axially directed path. The length of this part of tube 10 is assumed to be such that the transit time of the electrons between input electrodes 19, 19" and output electrode 15 is equal to at least a substantial fraction of a cycle of the high-frequency signal fed in at terminal 20 whereby a desired degree of delay will be obtained.

Since the distance of the electron beam from the tube axis in the region of coil 22 will be a function of the input voltage applied across deflecting electrodes 19, 19", a useful output could be obtained with target electrode 15 positioned immediately at the end of this coil or even within the magnetic field thereof. In accordance with another feature of the invention, however, I prefer to provide a second pair of horseshoe magnets 23, 23" between coil 22 and target 15, the polarity of these. magnets being opposite to that of magnets 21, 21" whereby the beam will be deflected outwardly, by an angle at least roughly proportional to the spacing of the beam from the tube axis, so that the loci of impingement of the electrons upon target 15 will be spread further apart and a larger target electrode, with improved signal-to-noise ratio, can be used.

The amplitude of the delayed output signal at terminals 17', 17" may be varied, according to another feature of the invention, by modifying the extent of the deflection of the beam under the-control of magnets 23, 23". For this purpose I have shown each of these magnets provided with an energizing winding 24", 24", respectively, connected across a source of current (not shown) by way of terminals 25, 25" in series with an adjustable impedance indicated schematically at 26.

FIGS. 3 and 4 show a devicesomewhat similar to that of FIGS. 1 and 2, comprising a tube 110 from whose cathode 112 emanates a beam 114. The position of this beam is controlled by two pairs of deflecting electrodes 119a', 119a" and 11%, 11%" which are cross-connected between ground and a signal input terminal 120 in such manner as to maintain the deflected beam parallel to the axis of the tube, as disclosed in my US. PatentNo. 2,728,894 issued December 27, 1955. The elongated central portion of the tube is surrounded by a focusing coiil122.

The output end of tube. 110 comprises an elongated conductor 123 positioned at right angles to the tube axis and energized from a source of direct current {not shown) via terminals 1253.125"; the intensity of this current may be controlled by suitable means such as the variable impedance 26 of FIG. 2. Conductor 123 is surrounded by a cylindrical, non-homogeneous magnetic field whose strength perpendicular to the median plane defined by the conductor and the beam axis, which is transverse to the plane of deflection of beam 114, is a maximum in said median plane and tapers off rather sharply on either side thereof, both because of the increasing distance from conductor 123 and by reason of the smaller angle enclosed between the circular lines of magnetic force and the beam. When the beam 114 is undeflected by a signal applied to terminal 120, the increasing magnetic field in the neighborhood of'conductor 123 forces the electrons onto a path of progressively decreasing radius of curvature, as shown in FIG. 4, until they reach a point closest to conductor 1 23 after which they are deflected away from this conductor over-a path symmetrical to the'path of approach. If the beam-has been originally skew to conductor 123, its magnetic deflection parallel to this conductor will be reduced and the electron path will be curved away from the median plane previously defined. A target electrode 115 of resistance material, provided with conductive terminal members 116', 116" from which connections extend to an output circuit not further illustrated which may be similar to that of FIG. 1, is in the form of a strip concentricwith conductor 123; strip 115 extends along a space curve in such manner as to intercept the electrons deflected by the magnetic field around conductor 123 in various positions of the beam.

From 'FIG. 3 it will be apparent that the point of im-' pingement of the electrons upon target 115 shifts considerably with relatively small deviations of the beam position from the tube axis. This sensitivity, on the other hand, may result in a certain dispersion of the electrons at the target, as illustrated, especially in the case of beams of appreciable cross section. Since, however, the voltage appearing across terminals 116', 116" will be determined by the means locus of impingement of the intercepted electrons, the output signal will not be materially afiected by this dispersion.

A magnetic field similar to that existing around conductor 123 may also be produced by a stream of free j trolledmeans is adapted to deflect said beamin one plane,

electrons. This has been illustrated in FIG. 5 where, by way of further modification, two electron currents 223', 223" parallel to a controlled beam 214 are generated .by' respective cathodes 227', 227", anodes 228, 228" and biasing batteries 229', 229". Beam 214, after passing along or parallel'to the axis of tube 210 through the field of a focusing 'coil 222, reaches a target electrode 21-5 after passing through a magnetic field'which is zero along the tube axis and reaches maximaof opposite sign adjacent, electron currents'223' and 223", being thus similar to the field produced by magnet 23'- and 23 in FIG. 1. It may be mentioned that,'-as illustrated, the presence of beam 214 will also tend tddeflect the electron currents 223', 223" from theirpath parallel to the tube axis; such defiection may, however, be minimized by imparting a sufficiently highvelocity'to the electrons emitted by cathodes 221 227 This velocity may be controlled,- for the purposeof varying thedegree of deflection of beam 214,,by means of potentiometers 231], -230. I

The invention is, of course,'not limited to the specific embodiments described and'illustratedjbut may be realized in various modifications, substitutions (e.g. of an electron beam similar to beam 223' for'conductor 123), adaptations or combinations without departing from the spirit and scope of the appended claims.

I claim: g

1. An electronic signal delay device comprising an elongated envelope, a source of electrons in said envelope, means for forming said electrons into a beam, a source of high-frequency signals, means controlled by said source of signals for deflecting said beamsubstantially parallel to a normal beam position, collector means for said electrons in said envelope spaced from said deflecting means by a distance such that the transit time of said electrons therebetween equals at least a substantial fraction of an oscillatory cycle of said signals, and magnetic focusing means positioned between said deflecting means and said collector means for minimizing deviations of said beam from parallelism with said normal beam position.

'2. A device according to claim 1 wherein said controlled means comprises source means for producing a steady transverse magnetic field, said field varying progressively in intensity and changing sign substantially in the region of the undeflected beam, and signal-response beam-deflecting means positioned ahead of saidfield.

- 3. A device according to claim 2 wherein said source means comprises a pair of inversely polarized magnets positioned on opposite sides of said region.

4. A device according to claim 1, further comprising signal-independent beam-deflecting means positioned between said focusing means and said collector means for causing divergence of the deflected beam from said normal beam position. I

5. -A' device accordingcto claim 4 wherein said beamdeflecting'means comprises source means for producing a steady "magnetic .field ahead of said-collector means.

' 6;-"A- device-according to claim 5 wherein said source means comprises a pair of inversely polarized rnagnets' said source means comprising means for producing current flow in saidplane parallel tosaid normal beam posi tion on opposite sides of. the latter. 9. -An' electronic signal-delay device comprising an elongated envelope, a source of electrons in said envelope, meansfor forming said electrons into a beam, a sdurceof high-frequency signals, signal-responsive beam-control means adjacent said source for deflecting said beam sub-. stantially parallel to itself and to a normal beam position; signal-independent beam-control means remote from said source for'causing divergence of the deflected beam from said normal beam position, and collector means for said electrons in said envelope at a location beyond said signal-independent beam-control means. 3 '10. A device according to claim 9 wherein'each of said beam-control means comprises means for producing a steady magnetic field transverse to said normal beam position, said fields-being parallel to each. other and increasing progressively with distance from said normal: bear'n' position. l

References Cited in the file of this patent UNITED STATES PATENTS Great Britain June 11, 1935 

